1. Field of the Invention
The present invention relates to a dry vacuum pump, and more particularly, to a dry vacuum pump that combines both the advantage of high compression ratio of the scroll-type vacuum pump, and the advantage of high exhausting speed of the rotary-vane vacuum pump, with simple structure, lower production cost and higher working effectiveness and quality.
2. Description of the Prior Art
The conventional rotary-vane pump 10, shown in FIG. 2, comprises a rotor 12, a pair of rotary vanes 13 and a stator chamber 15, wherein, a pair of vanes made of graphite are mounted on the rotor 12 through grooves thereon; in the interior of the stator chamber 15 a round-shaped rotating space 19 is formed and the rotor 12 is eccentrically positioned therein, with the rotor 12 and the pair of vanes 13 pressed by spring 18 coming into contact with the stator chamber wall 14 of the stator chamber 15. An inlet 11 and an outlet 17, both connecting the rotating space 19, are mounted on the stator chamber 15, with the opening and closing of the outlet 17 being controlled by an outlet valve 16.
Please further refer to FIG. 2 in accordance with FIG. 3 and FIG. 4. The rotor 12 is directly driven by motor to circularly rotate within the rotating space 19, during which the two vanes 13 begin to slide in the grooves of the rotor 12, with the ends of both vanes keeping contact with the stator chamber wall 14; since the two vanes are made of graphite, it is of no need to use vacuum pump oil to lubricate. Thus, by the movement of the rotor 12 and the vanes 13, the goals of introducing air through the inlet 11 and discharging air through the outlet 17 are to be achieved.
The advantage of such rotary-vane vacuum pump is the excellent exhausting speed, yet it has poor range of vacuum compression ratio.
The conventional scroll-type vacuum pump 20, shown in FIG. 5, comprises two scrolls 21 and 22, wherein, one scroll is a fixed scroll 21 that is a counter-clockwise helicoid, and the other scroll is an orbiting scroll 22 that is a clockwise helicoid. These two scrolls define a space (the air-introducing space 42, which is to be described later), and the orbiting scroll 22, being mounted on the eccentric of the motor driving crank, is driven to revolve but not self-revolving due to the restriction of the anti-self-revolving mechanism; such revolving motion is to form an orbiting motion, by which the orbiting scroll 22 is to rotate clockwise, thus air in the air-introducing space is to be compressed, and then air compressed is to be discharged through the central outlet hole 23.
The advantage of such scroll-type vacuum pump 20 is the high compression ratio, but since its motioning displacement is small, causing poor exhausting speed, it cannot be used for workload that requires higher exhausting speed, but only for lighter workload. The motor power can be expanded for such scroll-type vacuum pump 20 to increase the discharging (exhausting) speed, but the problem of overheating resulted therefrom shall acquire larger capacity of the cooling system.
The main object of the present invention is to provide a dry vacuum pump that combines the scroll-type vacuum pump and the rotary-vane vacuum pump, thus having the advantage of high compression ratio from the scroll-type vacuum pump, and the advantage of high exhausting speed from the rotary-vane vacuum pump, with simple structure, lower production cost and higher working effectiveness and quality.
The dry vacuum pump that achieves the aforementioned goals comprises a housing, with an inlet and an outlet; a rotary-vane vacuum pump, mounted inside the housing, including the rotor, a pair of rotary vanes and the stator chamber; a scroll-type vacuum pump, mounted inside the housing, including a fixed scroll and an orbiting scroll, and a motor-driven crank, used for driving the orbiting scroll of the scroll-type vacuum pump and the rotor of the rotary-vane vacuum pump. The rotary-vane vacuum pump is mounted on the side of the inlet, whereas the scroll-type vacuum pump is mounted on the side of the outlet, thus forming a conduit to connect both the rotary-vane vacuum pump and the scroll-type vacuum pump, for discharging and exhausting air, whereby air is introduced from the rotary-vane pump and discharged to the air-introducing space of the scroll-type vacuum pump, and then air is exhausted by the scroll-type vacuum pump.
The two vanes are mounted in the grooves of the rotor.
The vanes are made of graphite.
In the interior of the stator chamber a round-shaped rotating space is formed and the rotor is eccentrically positioned therein.
The rotor and the two vanes pressed by spring are to come into contact with the stator chamber wall of the stator chamber.
The inlet of the housing is connected to the rotating space of the stator chamber.
The outlet of the stator chamber is connected, via the channel of the housing, to the air-introducing space of the scroll-type vacuum pump, with the opening and closing of the outlet being controlled by an outlet valve.
The outlet of the housing is connected to the air-introducing space.
The rotary-vane vacuum pump and the scroll-type vacuum pump are adjacently mounted (e.g., by way of left-and-right juxtaposition) inside the housing; in addition, the housing is mounted with a right-end plate, and the ball-type anti-self-revolving mechanism is mounted between the right-end plate and the orbiting scroll of the scroll-type vacuum pump. Also a left-end plate is mounted in the housing located on the left side of the rotary-vane vacuum pump.